import { v4 as uuidv4 } from "uuid";
let UID                 = uuidv4();
let PLACE_HOLDER_REGEXP = new RegExp('(\\\\)?"@__(F|R|D|M|S|A|U|I|B|L)-' + UID + '-(\\d+)__@"', 'g');

let IS_NATIVE_CODE_REGEXP = /\{\s*\[native code\]\s*\}/g;
let IS_PURE_FUNCTION = /function.*?\(/;
let IS_ARROW_FUNCTION = /.*?=>.*?/;
let UNSAFE_CHARS_REGEXP   = /[<>\/\u2028\u2029]/g;

let RESERVED_SYMBOLS = ['*', 'async'];

// Mapping of unsafe HTML and invalid JavaScript line terminator chars to their
// Unicode char counterparts which are safe to use in JavaScript strings.
let ESCAPED_CHARS = {
  '<'     : '\\u003C',
  '>'     : '\\u003E',
  '/'     : '\\u002F',
  '\u2028': '\\u2028',
  '\u2029': '\\u2029'
};

function escapeUnsafeChars(unsafeChar) {
  return ESCAPED_CHARS[unsafeChar];
}


function deleteFunctions(obj){
  let functionKeys = [];
  for (let key in obj) {
    if (typeof obj[key] === "function") {
      functionKeys.push(key);
    }
  }
  for (let i = 0; i < functionKeys.length; i++) {
    delete obj[functionKeys[i]];
  }
}

function serialize (obj, options) {
  options || (options = {});

  // Backwards-compatibility for `space` as the second argument.
  if (typeof options === 'number' || typeof options === 'string') {
    options = {space: options};
  }

  let functions = [];
  let regexps   = [];
  let dates     = [];
  let maps      = [];
  let sets      = [];
  let arrays    = [];
  let undefs    = [];
  let infinities= [];
  let bigInts = [];
  let urls = [];

  // Returns placeholders for functions and regexps (identified by index)
  // which are later replaced by their string representation.
  function replacer(key, value) {

    // For nested function
    if(options.ignoreFunction){
      deleteFunctions(value);
    }
    // If the value is an object w/ a toJSON method, toJSON is called before
    // the replacer runs, so we use this[key] to get the non-toJSONed value.
    let origValue = this[key];
    let type = typeof origValue;

    if (type === 'object') {
      if(origValue instanceof RegExp) {
        return '@__R-' + UID + '-' + (regexps.push(origValue) - 1) + '__@';
      }

      if(origValue instanceof Date) {
        return '@__D-' + UID + '-' + (dates.push(origValue) - 1) + '__@';
      }

      if(origValue instanceof Map) {
        return '@__M-' + UID + '-' + (maps.push(origValue) - 1) + '__@';
      }

      if(origValue instanceof Set) {
        return '@__S-' + UID + '-' + (sets.push(origValue) - 1) + '__@';
      }

      if(origValue instanceof Array) {
        let isSparse = origValue.filter(function(){return true}).length !== origValue.length;
        if (isSparse) {
          return '@__A-' + UID + '-' + (arrays.push(origValue) - 1) + '__@';
        }
      }

      if(origValue instanceof URL) {
        return '@__L-' + UID + '-' + (urls.push(origValue) - 1) + '__@';
      }
    }

    if (type === 'function') {
      return '@__F-' + UID + '-' + (functions.push(origValue) - 1) + '__@';
    }

    if (type === 'undefined') {
      return '@__U-' + UID + '-' + (undefs.push(origValue) - 1) + '__@';
    }

    if (type === 'number' && !isNaN(origValue) && !isFinite(origValue)) {
      return '@__I-' + UID + '-' + (infinities.push(origValue) - 1) + '__@';
    }

    if (type === 'bigint') {
      return '@__B-' + UID + '-' + (bigInts.push(origValue) - 1) + '__@';
    }

    return value;
  }

  function serializeFunc(fn) {
    let serializedFn = fn.toString();
    if (IS_NATIVE_CODE_REGEXP.test(serializedFn)) {
      throw new TypeError('Serializing native function: ' + fn.name);
    }

    // pure functions, example: {key: function() {}}
    if(IS_PURE_FUNCTION.test(serializedFn)) {
      return serializedFn;
    }

    // arrow functions, example: arg1 => arg1+5
    if(IS_ARROW_FUNCTION.test(serializedFn)) {
      return serializedFn;
    }

    let argsStartsAt = serializedFn.indexOf('(');
    let def = serializedFn.substr(0, argsStartsAt)
      .trim()
      .split(' ')
      .filter(function(val) { return val.length > 0 });

    let nonReservedSymbols = def.filter(function(val) {
      return RESERVED_SYMBOLS.indexOf(val) === -1
    });

    // enhanced literal objects, example: {key() {}}
    if(nonReservedSymbols.length > 0) {
      return (def.indexOf('async') > -1 ? 'async ' : '') + 'function'
        + (def.join('').indexOf('*') > -1 ? '*' : '')
        + serializedFn.substr(argsStartsAt);
    }

    // arrow functions
    return serializedFn;
  }

  // Check if the parameter is function
  if (options.ignoreFunction && typeof obj === "function") {
    obj = undefined;
  }
  // Protects against `JSON.stringify()` returning `undefined`, by serializing
  // to the literal string: "undefined".
  if (obj === undefined) {
    return String(obj);
  }

  let str;

  // Creates a JSON string representation of the value.
  // NOTE: Node 0.12 goes into slow mode with extra JSON.stringify() args.
  if (options.isJSON && !options.space) {
    str = JSON.stringify(obj);
  } else {
    str = JSON.stringify(obj, options.isJSON ? null : replacer, options.space);
  }

  // Protects against `JSON.stringify()` returning `undefined`, by serializing
  // to the literal string: "undefined".
  if (typeof str !== 'string') {
    return String(str);
  }

  // Replace unsafe HTML and invalid JavaScript line terminator chars with
  // their safe Unicode char counterpart. This _must_ happen before the
  // regexps and functions are serialized and added back to the string.
  if (options.unsafe !== true) {
    str = str.replace(UNSAFE_CHARS_REGEXP, escapeUnsafeChars);
  }

  if (functions.length === 0 && regexps.length === 0 && dates.length === 0 && maps.length === 0 && sets.length === 0 && arrays.length === 0 && undefs.length === 0 && infinities.length === 0 && bigInts.length === 0 && urls.length === 0) {
    return str;
  }

  // Replaces all occurrences of function, regexp, date, map and set placeholders in the
  // JSON string with their string representations. If the original value can
  // not be found, then `undefined` is used.
  return str.replace(PLACE_HOLDER_REGEXP, function (match, backSlash, type, valueIndex) {
    // The placeholder may not be preceded by a backslash. This is to prevent
    // replacing things like `"a\"@__R-<UID>-0__@"` and thus outputting
    // invalid JS.
    if (backSlash) {
      return match;
    }

    if (type === 'D') {
      return "new Date(\"" + dates[valueIndex].toISOString() + "\")";
    }

    if (type === 'R') {
      return "new RegExp(" + serialize(regexps[valueIndex].source) + ", \"" + regexps[valueIndex].flags + "\")";
    }

    if (type === 'M') {
      return "new Map(" + serialize(Array.from(maps[valueIndex].entries()), options) + ")";
    }

    if (type === 'S') {
      return "new Set(" + serialize(Array.from(sets[valueIndex].values()), options) + ")";
    }

    if (type === 'A') {
      return "Array.prototype.slice.call(" + serialize(Object.assign({ length: arrays[valueIndex].length }, arrays[valueIndex]), options) + ")";
    }

    if (type === 'U') {
      return 'undefined'
    }

    if (type === 'I') {
      return infinities[valueIndex];
    }

    if (type === 'B') {
      return "BigInt(\"" + bigInts[valueIndex] + "\")";
    }

    if (type === 'L') {
      return "new URL(\"" + urls[valueIndex].toString() + "\")";
    }

    let fn = functions[valueIndex];

    return serializeFunc(fn);
  });
}


export default serialize